Purification of helium contaminated by nitrogen



Aug. 24, 1965 c. A. HERSTER PURIFICATION OF HELIUM GONTAMINATED BY NITROGEN Filed Jan. ll, 1962 OlVHVdSS BEOSSBHd M017 mmJOOU BOLVHVdBS sanssaad Hom uoivuvdss wnnaH aaaaosav nu Tn Rm. mr.. N H FVLA m5 E L R A H C gAGENT United States Patent O M 3,202,482 PURETECATON E HEL UM CNTAll/EENATEB BY NHTRGEN Charles A. Herster, Elmhurst, Nfii, assigner to Heii- Chem Products, inc., a corporation of Delaware ihded dan. 11, 1962, Ser. No. 165,574. 4 Ciaims. (Cl. 23--209) This application is a continuation-in-part of application Serial No. 807,345, filed in the name of Charles A. Herster, April 20, 1959, and now abandoned.

This invention relates to the separation of inerts from a gasiform mixture. In a particular aspect, this invention relates to the concentration of helium contained in natural gas.

Development of large-scale helium production operations since World War I is an interesting phase of chemical industrial growth. Of particular interest is the method of production in which helium is extracted in certain helium-bearing natural gases by processing at very low temperatures and relatively high pressures. Most of the helium has been produced by a method developed and used by the United States Bureau of Mines. Other methods have been developed but have not been used extensively for large-scale production.

Accordingly, it is a main object of the present invention to provide a convenient and improved method of recovering helium from a gasiform mixture.

Other objects and advantages of the present invention will become apparent from the accompanying description and disclosure.

It has been discovered that helium contained in a gaseous mixture which is substantially composed of nitrogen and hydrocarbons can be concentrated by process steps which comprise contacting the helium-containing gas mixture with liquid hydrocarbon oil in an absorption zone to remove higher hydrocarbons and a substantial portion of methane from the gas stream, cooling and fractionating said gas stream to remove a substantial portion of the nitrogen component and reduce the hydrocarbon content to a minor amount of methane in the gas stream, subjecting said gas stream to steam reforming conditions to increase the hydrogen content of the gas stream, contacting said gas stream with ammonia synthesis catalyst under conditions producing liquid ammonia, and hashing the liquid ammonia to recover the helium dissolved therein.

The drawing is a diagrammatic representation of a process system adapted for the practical application of the invention.

Referring to the drawing, the invention will be more fully explained as applied to the recovery of helium from natural gas. Raw gas from a natural gas source composed of approximately 14.0 to 17.0 percent nitrogen, 85.0 to 82.0 percent hydrocarbons and 0.3 to 0.7 percent helium is entered into a feed preparation unit through line 10. The gas enters a knockout drum to remove miscellaneous liquids and pipeline solids, and then is entered into a puriiication apparatus where it is contacted with monoethanolamine to remove carbon dioxide and hydrogen sulde. Usually, the monoethanolamine treatment is followed by an aqueous sodium hydroxide wash step to completely remove all traces of these compounds. The gas is separated from the caustic solution and contacted with Water in a water wash drum to remove traces of entrained caustic. The gas is dried, compressed and 3,2%,482 Patented Aug. 24, i965 then passed through a cooler to remove the heat of compression that is produced.

The cooled gas, which may or may not contain condensed materials, is passed through line 11 into absorber tower 12 where the gas is contacted with a lean oil which is substantially liquid propane. The lean oil selectively absorbs methane and heavier gases. lntercoolers are provided to remove a portion of the heat of absorption so as to avoid an excessive rise in the temperature of the absorption oil owing down the tower.

Liquid from absorber tower 12, consisting of condensed material from the feed gas plus the rich oil, passes through line 13 by gravity or pumping to a desorber systern 14. Here the addition of heat by a reboiler at the base of the desorber tower, combined with the desired number of fractionation trays, .permits the selective desorption from this liquid of the small quantities of nitrogen, hydrogen and helium which :are picked up in absorber tower 12 when methane absorption is set at some practical level, such as percent absorption. The stripped desorbed vapors pass through line 15 into absorber tower l2 of the absorption system. rlfhe desorber bottoms is entered into a de-ethanizer preheater wherein heat is removed from the pipeline feed gas. The deethanizer feed is then passed into the de-ethanizer. In the de-ethanizer, most of the methane and ethane, and some of the propane in the de-ethanizer feed are passed overhead as a vapor stream. This stream is entered into a condenser where cooling is applied to provide adequate liquid for reflux which is separated from the non-condensed vapor in a reflux drum and returned to the deethanizer tower. The overhead product vapor is entered into an exchanger to abstract heat from pipeline feed gas, and is then sent to the pipeline or another process unit, as required.

The de-ethanizer tower produces a bottoms product which contains little ethane and substantially all of the propane, butane and heavier hydrocarbons contained in the desorber bottoms. Stripping vapor is produced in the de-ethanizer tower by a reboiler, Bottoms product ows from the de-ethanizer tower into a depropanizer tower.

The depropanizer tower produces an overhead product of ethane, propane and a small quantity of butane. Part or all of this material is refrigerated and returned to absorber tower 12 as a source of lean oil.

Gross overhead vapor from the depropanizer is entered into a condenser where it is totally condensed and withdrawn and then passed into a reflux drum. Reflux from the drum is returned to the depropanizer tower. Lean oil is withdrawn from the reux drum, refrigerated and pumped to absorber tower 12. There may be excess overhead material after satisfying the lean oil requirement, or additional lean oil may be needed depending upon the level of methane recovery at which the system is operating.

Net product propane is passed into storage. If makeup propane is required, then it is obtained from the storage source.

Bottoms product from the depropanizer, containing a small amount of propane plus most of the butanes and heavier hydrocarbons in the feed gas, is cooled and passed into storage.

Absorber tail gas is withdrawn from absorber tower 12 and entered into nitrogen-hydrocarbon rejection system 17 through line 16. The gas stream is divided into two portions. an exchanger and loses heat to bottoms product from the nitrogen-methane balancing unit of rejection system 17.

lThe second portion of the gas is passed ythrough an exe changer which is the reboiler for the balancing unit nitrogen tower. Cooled gas from the two exchangers are combined and entered into yanother vexchanger Where heat is removed by nitrogen tower overhead product. The gas is then passed into another exchanger where final cooling is effected by refrigeration. The cooled gas is entered into the nitrogen tower.V Gross overhead vapor from the nitrogen tower is passed into a condenser where suficient reilux liquid is condensed to elect the desired separation. v The vapor-liquid mixture'is then entered into a reflux drum. The liquid from the drum is pumped to the top ofthe nitrogen tower to provide reflux. The vapor separated in the refluxV drum is enteredV into the exchangers described above. The resultant gasV is with- The iirst portion of the gas is entered into bon dioxide not removed Yby monoethanolamine treat- Y ment are converted to methane by reaction with hydrogen previously produced steam-methane reforming system drawn from the nitrogen-hydrocarbon rejection system i Y 17 through-line l5? `and entered into steam-methane reforming system 20. Y i

VThe nitrogen tower bottoms exchangers described above. The heated bottoms is -withdrawn as a gas and returned to the pipeline or to another processing unit as required. Y Y g In steam-methane reforming system 20, methane is converted to hydrogen with by-product carbon dioxide in the presence of steam. The product gas from the reforming system after carbon dioxide removal andmethanation is Vsuitable as an ammonia synthesis feed gas. Y

The nitrogen tower overhead product is joined with steam Vand the'mixture is combined with ammonia synthesis system 22 helium-nitrogen-hydrogen recycle coming through line 48. The resultant mixture is heated in an exchanger and entered into the steam reforming furnace. Here, in the presence of nickel-containing catalyst, the methane reacts with water to form hydrogen, carbon monoxide and carbonY dioxide. The reformed gas is passed through a waste heater 'boiler Wherein'steam is Y generated and the gas is quenched. VThe cooled gas'is entered into a shift reactor where,in'the presence ot added steam and promoted-iron catalyst, the carbon -rnonoxide is converted to carbon'dioxide which thereby produces further amounts of hydrogen. The gas from the shift reactor is then passed into a steam boiler for heat recovery. The cooled gas from the steam boiler is enteredinto an absorber tower where it is contacted with monoethanolamine solution to remove carbon dioxide.

The monoethanolamine treatment system usually includes regeneration facilities such as that described below.

Vdrawn from the overhead drumY and sentto storage or other processing unit. Condensed amine and water is withdrawn from the overhead drum and ows back'to the stripper tower.

lean amine-rich amine exchanger mentioned above.V This is passed through the two Here the addition ofV The stripped amine which Vis the v bottoms` product from the stripper Vtower is entered into the entered into a heater.

The methanated gas is passed through the feed-effluent exchanger mentioned above where it is cooled and Vmost of the 'water is condensed. The cooled gas from the exchanger is further cooled in another exchanger and then passed into a drumY where condensed water is separated from the gas stream. The water that is withdrawn from the drum is either sent to storage or employed in another service. The cooled gas .withdrawn from the drum is passed through a multistage compressor which includes intercoolers, after-coolers and connected piping and drums. The compressed gas is then passed through an oil filter where traces ofl entrainedlubricating oil from the compressor are removed from the gas stream. The gas is withdrawn from the compressor system and passed Vthrough line 21 to ammonia synthesis system 22.

In ammonia synthesis system 22 the-synthesis eluent gas is withdrawn through Vline 23 and entered into high pressure separator 24. In the Vhigh pressure separator,

' with feed gas coming from steam-methane reforming systemV 2) andentered into the Vammonia synthesis reactor where itis subjected to ammonia synthesis conditions such that nitrogen and hydrogen are reacted in the presence kof ammonia synthesis catalyst. The ammonia synthesis reactor eluent is passed into a condenser where it is cooledV by water. 1' lt is thenV Withdrawn and entered into high pressure separator 24, thus completing this circuit( The quantity of this recycleportion of high pressure separator vapor may be adjusted to modify the Vhydrogen-nitrogen ratio in the ammonia converter such that optimum reaction conditions are achieved at a rela- Vtively'highV concentration `of hydrogen plus nitrogen 1n the recycle gas, thus'lreeping the recycle gas rate required f at a low level.

-Rich monoetha'nolamine (monoethanolamine plus Y absorbed carbon dioxide) is withdrawnrtrom the bottom' of f TheV second Vstream of the divided high pressure sepafrator V24 gas passes through line 2t?, and is combined with high pressure separator 24 liquid which is withdrawn from separator Z4 through line 29. The mixture is passed Y throughrheater 30 and then entered into helium separator 32'throi1gh Vline 31'.V The liquid from helium-separator 32 isfwithdrawn through line'33 and a pressure-reduc-V valve and entered into cooler 34. The cooled stream passes througlrline 35 to low pressure separator 36. Substantiallyv pure liquid ammonia from separator 36 is withdrawn through line'37, cooled, and passed to storage.

drum'42 through line 43 and joined to lineY 35 at the cooled lean amine is'withrdravvn,V further cooled in another exchanger and thenV chargedto the ethanolamine absorber tower.

Thetreated gas is withdrawn'overhead v from the ethanolamine absorber tower as Yvapor and passed to a methanation systern.- in theme'thanation system the small amounts Yof carbon monoxideremainingV Y inlet of low pressure separator 36. The vapor from drum 42 ilows .throughV line 44 to'water wash tower 45.1 Water enters this tower through line 46 and dissolvesamrnonia `vaporin'tl're gas'.A The aqua ammonia produced is with-` drawn from the base of tower 45 through line 47. The vapor from wash tower 45 is Vwithdrawn throughV line 48 Yand vreturned to steam reforming system Z9 as previous-.

ly described.

into a drum. Condensed liquid ammonia is withdrawn from the drum and returned to the inlet of low pressure separator 35. The vapor from the drum is contacted with water in a wash tower to remove dissolved amomnia vapor from the gas. Aqua ammonia is Withdrawn from the bottom of the wash tower. The vapor from the wash tower passes out of helium purification system Si) through line 51 as a crude helium stream suitable for further purication such as is described below. The high pressure separator and helium separator are actually two high pressure separators operated at diiferent temperatures which, in independent manners, edectively control recycle gas quality and helium net gas quality.

Further purification of the crude helium stream can be accomplished by methods known and used in the art. Illustratively, the crude helium vapor from the helium wash tower is entered into a catalytic oxidizer unit. Oxygen of about 95 percent or higher purity is contacted with the gas stream under proper control to combust the hydrogen and methane with-out leaving an excess of oxygen in the effluent stream. To promote the reaction platium catalyst is employed in the oxidizer unit.

Elluent from the oxidizer unit is passed through a conventional carbon dioxide removal system, such as the monoethanolarnine absorber system previously described. The carbon dioxide-free helium gas is compressed, passed through an oil filter and then dried. The resultant heliumbearing stream is passed to storage or submitted to final super-purification.

The following example illustrates a typical operation within the scope or" the present invention. It is appment that speciiic compositions of materials and conditions can be varied considerably without departing from the invention in its broadest interpretation.

Example With reference to the drawing, well gas at a pressure of about 620 p.s.i.a. is passed `into the process system at a rate providing the moles per hour flow of gas components as indicated below. After the gas has been treated to remove miscellaneous liquids and pipeline solids, it is contacted with mono-ethanolamine lto remove carbon dioxide and hydrogen suh'ide. The gas is then washed with aqueous sodium hydroxide solution, dried and compressed. After 'the heat of compression is removed and urther cooling is eected, the gas stream is passed through line 11 into absorber tower 12. Liquid from absorber tower 12 passes through line 13 to desorber system 1d. The material balance of the Iabsorber system is indicated below.

Line 11 1G 15a Desorber Raw Absorber Absorber Absorber bottoms Component pipeline feed gas tail gas lean oil gos Nitrogen 3, 452 3, 452 3, 452 0 0 Hydrogen 22 22 O D Carbon dioxidc 22 0 (1 0 0 Helium 110 110 110 0 0 Methand 16, 535 1G, 4, 150 0 12, 385 Ethaue 1,011 1,011 10 50 ,0 Propane 506 506 406 12, O00 12, 100 Isobutane S8 SS G 0 88 n-Butane 154 154 O 0 154 Isopentane 44 @A t) U 44 Pent-nue 22 22 0 O 22- C and higher 22 22 O 0 22 Total 21, 98S 2l, 966 8, 150 12, 050 25, S66

The desorber tower bottoms is passed to the cle-ethanizer where moet of the methane and ethane and some propane are passed overhead as a vapor stream. The de-ethauizer bottoms product is passed into the depropauizer tower. IThe material balance for the de-ethanizer and depropanizer systems is indicated below.

De-ethanizer Depropanizer Component Net Overhead Bottoms overhead Bottoms product (excluding lean oil) Methane 12, 385 0 0 0 1,001 so o o 12,000 o 0 0 88 0 88 0 154i 0 154 0 44 0 44 0 22 0 22 0 22 0 22 Total 13, 486 12, 380 0 330 Absorber tower 12 tail gas is withdrawn through line 16 through heat exchangers and entered into nitrogen tower 17. Net overhead vapor from nitrogen tower 17 is withdrawn through line 12. The nitrogen tower 17 bottoms is withdrawn through line 1S. The following table indicates the material balance relating to the nitrogen tower and to the low pressure separator 36 recycle, which enters through line 43 and is combined with net nitrogen tower overhead vapor.

The nitrogen tower overhead product through line 19 is joined with steam and combined with ammonia synthesis system 22 recycle as previously described and entered into the steam reforming furnace. The reformed gas is treated in the shift reactor where, in the presence of added steam and promoted-iron catalyst, carbon monoxide is converted to carbon dioxide. The gas is then contacted with monoethanolamine in an absorber tower to remove carbon dioxide. The treated gas is withdrawn from the absorber tower and entered into a methanation unit where traces of carbon monoxide and carbon dioxide in the product gas are reacted with hydrogen in the presence of a nickel-containing catalyst to provide a stream suitable as ammonia synthesis feed gas. The material balance involved in the steam-methane reforming system is indicated below.

The gas stream from the reforming system is entered into ammonia synthesis system 22. Ammonia synthesis effluent gas in line 23 is entered into high pressure separator 24. In the separator, the vapor is separated from the liquid and passes out through line 25 where it is split into two separate streams. The rst'stream passes Ythrough line 27 and is recycled to ammonia synthesis and high pressure separator 24 is indicated below:

The liquidV from heliumseparator 312 isV withdrawn through line 33, cooled and entered into low pressure to mixtures containing asl muchas 25 percent ethane or 60 percent butane. The rich oil flowing from the absorber tower to thev desorber tower is maintained at a temperature of between about 125 F. and 225 F.

. material balance of the ammonia synthesis system 22 gas passes out of the absorber at a temperature of between about 10 F. and 190 F.

The rich oil entersiinto the desorber tower at a pressure of between 400 and 1,400 p.s.i.a. The overhead vapor ensuing from thedesorber tower has a temperature of between about 40 F. and 120 F. and the desorber tower bottom pass out of the desorber at a temperature of between about 30 F..and 110 F.

Desorber bottoms is passed into the de-ethanizer tower at a pressure of between about 200 and 600 p.s.i.a. The vapors from the de-ethanizer tower are withdrawn'at a temperature of between about 50 F. and 150 F. and the bottoms from the tower are maintained at a temperature of between about 125 F. and225 Ff y The de-ethanizer bottoms enters the depropanizer towe at a pressure of Vbetween about 175 and 300 p.s.i.a. The depropanirzer overhead vapor iswithdrawn at a temperature vof betweenV about 85 F. and 130 F. and the botseparator 36. The liquid from separator 36 is withdrawn through line 37 as substantially pure ammonia. The vapor from separatorV 36 isV Withdrawn through line Y38 and passed on through cooler 39 to drum 42. 'Condensed ammonia from drum 42 owsV through line V43 tothe inletV of separator 36. The vapor from drum 42 'flows through line 44 to wash tower 45 where ammonia vapor is washed out of the gas. The aqua ammonia produced is withdrawn through line 47. The vaporV from wash tower 45 is passed Yout through line 48 and is returned to the steam reforming unit as previously described. i

The vapor from the helium Vseparator is withdrawn through line 49, washed with waterto remove ammonia vapor, and passed out of theV system as a crude helium stream suitable for further purication as previously described.V The material balance of the helium separator"V and the low pressure separator is indicated below;

In the treatment of natural gas as describediin the above example, the raw gas stream at wellheadV pressure is entered Vinto invention purification system Vat a rate of aration system well brine, hydrocarbon liquid, pipeline solids and other miscellaneous materials are removed.

The natural gas is contacted with monoethanolamine at a temperature of between about 40 F. and 180 F.V Car-bon dioxide removal can be accomplished with water or with diethanolamine,triethanolamine, caustic and other conventional alkaline materials,YV The carbonV dioxide- Y about 22,000 total gas moles Vper hour. In the feed prepfree gas is contacted with activated alumina or other standard drying agent.

Y is employed at a temperature of-.between Vabout 0 F.

Thev dried gas is compressed to aV 'Y Vv.pressure between 500 and 1,500 p.s.i.a. and passed into about 50 and 300 p.s.i.a.

tomsY are withdrawn at a temperature of between about F. and 260 F.

In nitrogen-hydrocarbon rejection system 17 the nitrogen tower pressure is maintained at between about 200 and 800 p.s.i.a.V The overhead vapor product from the nitrogen tower is withdrawn ata temperature between about 100 F. and 300 F. and the bottoms are withdrawn at a temperature of between about 100 F. and

Y' The feed gas pressure in steam-methane reforming system 20 is between about 100 and 400 p.s.i.a. Nickel oxide is the preferred catalyst in the reforming funace.

The space velocity in the furnace is between 2,000 andV The reformed gas passes out of the reforming furnace at a temperature of about lll-00F. to 1800 F. and a pressure Kof between about 50 and 300 p.s.i.a.

Y The catalyst Vin the shift converter is preferably chromium-promoted iron dioxide. Steam is introduced into the converter'to provide between about 0 and 2 moles of water per atom of carbon. The gas stream is withdrawn from the shift converter ata temperature in the rangeV between about 650 F. and 850 F. and a pressure between Y After the converter treatment the carbon dioxide in the gas-stream is removed in a conventional monoethanolamine absorber regenerator system. The carbon dioxide pickup ratio is approximately 3v to 5 s.c.f. carbonV dioxide per gallon of monoethanolamine. Y Theaverage conditions in the monoethanolamine absorber are a temperature between about 40 F. and

180 F. a pres-Sure betweenabout 200 and 600 p.s.i.a.

The catalyst in the methanation system preferably contains nickel asithe active agent. The space velocity of the gas stream through the methanation system is between about 2,0001and 8,000 s.c.f/h. gas per cubic foot of catalyst. The outlet conditions ofthe methanation system are a temperatureibetv'veenY about Vi500"V F. to 700 F. and a pressure ofY about 200 and 600 p.s.i.a.

High pressure separatorf24 is operated at;a pressure between about 6,000 and 20,000.p.s.i.a. and a temperature between about 40 F. "and 150 F. Therecycle gas f from the high pressure separator varies in quantity from Y O'to about 55 percent of Vthermoles of ammonia synthesis feed gas. ,'Ifhe preferred catalyst for the ammonia synthesis converter is iron oxide promoted with alkali oxide. The space velocity of the gas stream through the converter'is-between'about 20,000 to 50,000 s.c.f./h. of exit gas per cubic foot of catalyst.

i perature is between about 800 VF. and l200 F. and the Yand 200 F. LeanV oilV composition may `rangeV from-..v

propane with less than 5 percent-each ofvethane or butane second Vconverter outlet temperature is between 800 F.V and 1200F. Y v

The firstV converter tem- The helium separator 32 is operated at a pressure between about 6000 and 20,000 p.s.i.a. and a temperature between about 130 P. and 230 F.

The low pressure separator 36 is operated at a pressure between about 200 and 2,000 p.s.i.a. and a temperature between about 40 F. and 155 F.

As mentioned previously, the crude helium withdrawn from the system through line 5l is suitable for further purification. The crude helium feed stream consists of the net purge vapor from the process plus liquid ammonia with dissolved gas from high pressure separat-or 24 in the ammonia synthesis system. The ammonia is removed with a water wash at a temperature between about 40 F. and 100 F. and a pressure between about 500 and 2,000 p.s.i.a. The washed helium-bearing gas stream is passed into a catalytic oxidation reaction system preferably containing platinum as the active agent to remove hydrogen and hydrocarbon components from the gas stream by oxidation. Carbon dioxide and water are removed with a conventional monoethanolamine system preceded by 20 cooler and Water separator drums, The resultant helium rich gas stream is subjected to a nal drying over activated alumina desiccant beds.

What is claimed is:

l. Tn a process for recovering helium from natural gas, the steps which comprise contacting natural gas with liquid hydrocarbon oil which is substantially propane in an absorption zone to remove higher hydrocarbons and a substantial portion of methane from the gas stream, cooling and fractionating said gas stream to remove a substantial portion of the nitrogen component and reduce the hydrocarbon content to a minor amount of methane in the gas stream, subjecting said gas stream to stream reforming conditions to increase the hydrogen content of the gas stream, contacting said gas stream with ammonia synthesis catalyst under conditions producing liquid ammonia, and flashing the liquid ammonia to recover helium dissolved therein.

2 The process of claim l wherein said cooling and Il@ 'fractionation step is controlled to provide the optimum ratio of nitrogen to hydrogen for the ammonia synthesis step.

3. In a process for recovering helium from natural gas, the steps which comprise contacting natural gas with liquid hydrocarbon oil which is substantially propane in an absorption zone to remove higher hydrocarbons and a substantial portion of methane from the gas stream, cooling and fractionating said gas stream to remove a substantial portion of the nitrogen component and reduce the hydrocarbon content to a minor amount of methane in the gas stream, subjecting said gas stream to steam reforming conditions to increase the hydrogen content of the gas stream, contacting said gas stream with ammonia synthesis catalyst under conditions producing liquid ammonia, dashing the liquid ammonia to produce a heliumrich vapor phase separate from said liquid ammonia, recycling a portion of said vapor phase vto the ammonia synthesis system, contacting the remainder of said heliumrich phase s net purge gas with the said liquid ammonia phase to remove diluent components and thereby providing a higher helium content in the resulting gas stream.

4. The process of claim 3 wherein the dissolved gaseous diluent components are ashed from the liquid ammonia Wash phase and recycled to the steam reforming system.

References Cited by the Examiner UNITED STATES PATENTS 1,658,631 2/28 Dannenbaum 23-209 1,875,926 9/52 Hughes 23-199 2,610,106 9/52 Gray 23-199 3,088,919 5/63 Brown et al. 23-2 X OTHER REFERENCES yteller: Comprehensive Treatise on inorganic and Theoretical Chemistry, vol. 7, pages S93, 895.

MAURICE A, BRNDISI, Primary Examiner. 

1. IN A PROCESS FOR RECOVERING HELIUM FROM NATURAL GAS, THE STEPS WHICH COMPRISE CONTACTING NATURAL GAS WITH LIQUID HYDROCARBON OIL WHICH IS SUBSTANTIALLY PROPANE IN AN ABSORPTION ZONE TO REMOVE HIGHER HYDROCARBONS AND A SUBSTANTIAL PORTION OF METHANE FROM THE GAS STREAM, COOLING AND FRACTIONATING SAID GAS STREAM TO REMOVE A SUBSTANTIAL PORTION OF THE NITROGEN COMPONENT AND REDUCE THE HYDROCARBON CONTENT TO A MINOR AMOUNT OF METHANE IN THE GAS STREAM, SUBJECTING SAID GAS STREAM TO STREAM REFORMING CONDITIONS TO INCREASE THE HYDROGEN CONTENT OF THE GAS STREAM, CONTACTING SAID GAS STREAM WITH AMMONIA SYNTHESIS CATALYST UNDER CONDITIONS PRODUCING LIQUID AM- 